From: Ben Widawsky <ben@bwidawsk.net>
To: Jani Nikula <jani.nikula@linux.intel.com>
Cc: intel-gfx@lists.freedesktop.org
Subject: Re: [PATCH 1/7] drm/i915: Mark context switch likely
Date: Fri, 5 Apr 2013 09:44:54 -0700 [thread overview]
Message-ID: <20130405164453.GA23599@bwidawsk.net> (raw)
In-Reply-To: <87d2u9qwqh.fsf@intel.com>
On Fri, Apr 05, 2013 at 10:09:58AM +0300, Jani Nikula wrote:
> On Fri, 05 Apr 2013, Ben Widawsky <ben@bwidawsk.net> wrote:
> > Only the very first switch doesn't take the path.
> >
> > Signed-off-by: Ben Widawsky <ben@bwidawsk.net>
> > ---
> > drivers/gpu/drm/i915/i915_gem_context.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/gpu/drm/i915/i915_gem_context.c b/drivers/gpu/drm/i915/i915_gem_context.c
> > index 94d873a..aa080ea 100644
> > --- a/drivers/gpu/drm/i915/i915_gem_context.c
> > +++ b/drivers/gpu/drm/i915/i915_gem_context.c
> > @@ -390,7 +390,7 @@ static int do_switch(struct i915_hw_context *to)
> > * is a bit suboptimal because the retiring can occur simply after the
> > * MI_SET_CONTEXT instead of when the next seqno has completed.
> > */
> > - if (from_obj != NULL) {
> > + if (likely(from_obj)) {
>
> Looking at the function, is this, uh, likely to make a difference?
>
Probably not.
> Same goes for the unlikely in patches 4/7. (Yes, patch_es_ 4/7 - there's
> *two* patches 4/7 in the series! :o)
I don't see two, weird.
>
> I'm just generally wary of adding (un)likely annotations. I don't think
> it matters that the annotation itself is obviously correct; IMHO the
> performance impact should matter.
>
> </bikeshed>
Right. I actually stuck it in by accident, and decided to keep it only
because it serves as nice documentation. I suppose a comment would do
the same thing, but this also had a chance (albeit slight) to improve
things.
>
> BR,
> Jani.
>
>
> > from_obj->base.read_domains = I915_GEM_DOMAIN_INSTRUCTION;
> > i915_gem_object_move_to_active(from_obj, ring);
> > /* As long as MI_SET_CONTEXT is serializing, ie. it flushes the
> > --
> > 1.8.2
> >
> > _______________________________________________
> > Intel-gfx mailing list
> > Intel-gfx@lists.freedesktop.org
> > http://lists.freedesktop.org/mailman/listinfo/intel-gfx
--
Ben Widawsky, Intel Open Source Technology Center
next prev parent reply other threads:[~2013-04-05 16:42 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-04-04 23:41 [PATCH 0/7] [RFC] Context reference counting Ben Widawsky
2013-04-04 23:41 ` [PATCH 1/7] drm/i915: Mark context switch likely Ben Widawsky
2013-04-05 7:09 ` Jani Nikula
2013-04-05 16:44 ` Ben Widawsky [this message]
2013-04-05 21:36 ` Daniel Vetter
2013-04-08 6:06 ` Jani Nikula
2013-04-04 23:41 ` [PATCH 2/7] drm/i915: Move context special case to get() Ben Widawsky
2013-04-05 10:41 ` Ville Syrjälä
2013-04-05 16:49 ` Ben Widawsky
2013-04-04 23:41 ` [PATCH 3/7] drm/i915: Make object aware that it backs a context Ben Widawsky
2013-04-04 23:41 ` [PATCH 4/7] drm/i915: A bit better messaging for contexts Ben Widawsky
2013-04-04 23:41 ` [PATCH 4/7] drm/i915: Better context messages Ben Widawsky
2013-04-04 23:41 ` [PATCH 5/7] drm/i915: Track context status Ben Widawsky
2013-04-04 23:41 ` [PATCH 6/7] drm/i915: Store last context instead of the obj Ben Widawsky
2013-04-05 7:51 ` Chris Wilson
2013-04-05 17:28 ` Ben Widawsky
2013-04-04 23:41 ` [PATCH 7/7] drm/i915: Print all contexts in debugfs Ben Widawsky
2013-04-04 23:41 ` [PATCH 0/7] [RFC] Context reference counting Ben Widawsky
2013-04-05 4:52 ` Ben Widawsky
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